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Finding the Fourth Proportional to 390.86, 539.40 and 216.21

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Solution

The fourth proportional to 390.86, 539.40 and 216.21 is: 298.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.86 : 539.40 = 216.21 : x
  2. Step 2: Convert to fraction form
    390.86/539.40 = 216.21/x
  3. Step 3: Cross multiply
    390.86x = 539.40 × 216.21
  4. Step 4: Simplify right side
    390.86x = 116,619.90
  5. Step 5: Solve for x
    x = 116,619.90/390.86
  6. Step 6: Final answer
    x = 298.37

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.